A retired four-star U.S. Navy admiral was sentenced on Tuesday to six years in prison for his conviction on corruption charges that he agreed to exchange a military contract for a lucrative postretirement job. Retired Adm. Robert P. Burke — once the second-highest uniformed officer in the Navy — was commanding its forces in Europe and Africa when he engaged in a bribery plot with two business executives, according to federal prosecutors. A jury convicted Burke of four counts, including conspiracy and accepting a bribe, after a trial in May. A separate trial for Burke’s two co-defendants — Next Jump co-CEOs Yongchul “Charlie” Kim and Meghan Messenger — ended with a hung jury and a mistrial last Thursday.